Binding assays are routinely used to screen for and diagnose a whole host of diseases and conditions, including Lyme disease, herpes, acquired immunodeficiency syndrome, streptococcal infections, lupus and pregnancy, to name just a few. Such assays are relatively simple in theory, utilizing the binding affinity between two or more binding members to detect and/or quantify the presence of one of the members, referred to herein as the analyte. Binding members comprise a wide range of substances, including antigens, antibodies haptens, complimentarynucleic acid sequences, ligands and receptors, with antigen-antibody binding member pairs used in immunoassays currently enjoying the most widespread use.
One common format of a binding assay involves immobilizing a binding member specific for the analyte on a paperlike sheet or membrane. The membrane is then contacted with the test sample and appropriate reagents under conditions allowing binding to occur between the immobilized binding member and any analyte present in the sample, with means for detecting binding events also provided. Often a labelled second binding member which binds to the first binding member-analyte complex is added to provide a detectable signal on the membrane.
In the assay format described above, i.e. where the vehicle for the assay is a binding member immobilized on a membrane, a variety of devices and techniques have been developed for testing more than a single sample per membrane. For example, as described in my U.S. Pat. No. 4,834,946 and U.S. Pat. No. 4,713,349, a membrane is secured between two plates and samples applied in multiple plate channels. The devices and techniques currently available, however, require a significant degree of handling of the samples and membrane, increasing the possibility of contamination and widening the margin for human error. Thus there remains a need for an improved binding assay device for the accurate and efficient assaying of multiple samples which is convenient, easy to use, and which requires minimal handling of the assay components. Such an assay device is provided in accordance with the principles of the present invention.